Only die-hard romantics will be able to stomach the surging waves of sentiment that overwhelm this British drama. There are some terrific moments along the way, and an expert cast that just about holds things together, but the characters and situations are only sketchily developed as writer-director Curtis races to cram far too much into an overlong movie.

Tim (Gleeson) grew up in idyllic splendour on the Cornish coast with his quirky-smart parents (Nighy and Duncan), manic earth-loving sister Kit Kat (Wilson) and perpetually confused Uncle Desmond (Cordery). Then on his 21st birthday, his dad tells him that the men in the family can travel through the timeline of their lives. So Tim decides to use this to find love. It takes awhile, but when he moves to London he meets Mary (McAdams), a charming, unflashy American. And he uses his time-traveling ability to make their life as amazing as possible.

As always, Curtis populates the screen with people who are well-off even though they have jobs that would never pay enough to buy a house in, say, Maida Vale. We never see Tim use his gift to win the lottery, but that could be one explanation. This is also a fantasy London stripped of its diversity: there isn't a non-white or non-straight person in sight. So time-travel is perhaps the film's most believable element.

Thankfully, Curtis is skilled at writing offhanded dialog, which the cast delivers expertly. Nighy is especially good in a prickly role that's funny and endearing. Gleeson is essentially the Hugh Grant figure here: awkward, hopeful and disarmingly adorable. Everyone else is one-note, like Hollander's perpetually angry playwright. And the women are even less than that: Duncan has some impact in a few thankless scenes, while McAdams is cute and never quite there.

But then, nothing quite comes into focus. Scenes are shot in close-up, making it tricky to get the full picture. And the narrative uses gimmicky montages to lurch through about 10 years, glibly dealing with weddings, funerals, births and sudden tragedy. And in the first act, Tim's time-travel is actually rather sleazy. That said, there are scenes that can't help but make us laugh or tear-up, even if the series of big emotional endings seems to go on forever.